US2095273A

US2095273A - Dehairing and bating of skins and hides

Info

Publication number: US2095273A
Application number: US36326A
Authority: US
Inventors: Wallerstein Leo; Pfannmuller Julius
Original assignee: Wallerstein Co Inc
Current assignee: Wallerstein Co Inc
Priority date: 1935-08-15
Filing date: 1935-08-15
Publication date: 1937-10-12
Anticipated expiration: 1954-10-12

Description

Patentedoct. 12, 1937 narmmmo aim ENT OFFICE Leo Wallerstein and Julius Hanmnnller, New York, N. Y., assignora to Waller-stein Company, Inc., incorporation of New York No Drawing- Application mm 15, 1935,

Serial No. cases 11 Claims. (in. 195-6) The present invention relates to improvements in the bating and dehairing of skins and hides.

In dehairing and bating skins and hides, the

usual process has been to employ an'alkalilsuch as lime, and/or sulfide materials, such as calcium or sodium sulfide for changing the condition .of the skin or hide so that the hair may be readily removed therefrom. The dehairing operation is followed by a bating operation involving the utilization of an infusion or extraction of dung, such as dog dung or pigeon dung.

Dehairing and bating respectively involving the successive utilization of alkali and/or sulfides and of dung infusions were particularly diflicult to control, and there was always a possibility of spoilage or serious deterioration of the skins or hides. In addition these processes involving sulfides' and also involving unpleasant smelling and odoriferous dung materials create unsanitary l0 and unhealthy working conditions which greatly increase expense and difliculty of production.

It has been suggested that the bating and/or dehairing of skins and hides might be accomplished by the use of enzymes, but considerable difliculty was encountered in controlling the bating or dehairing action when both were caused to take place simultaneously and/or in the'same bath, and particular difficulty was experienced in obtaining a uniform and high quality product without considerable skill and exacting control.

An object of the present invention is to provide a dehairing and bating process of skins and hides which will provide skins and hides of improved quality and characteristics and according to which substantially the same enzymatic liquor may be utilized for both the dehairing and bating operation under accurately determinable and controllable conditions.v j

It has now been found that skins and hides may be successively dehaired and bated by the same enzymatic materials provided the conditions of the dehairing and/or hating operation are carefully controlled with resultant enhancement of the possibility of controlling the quality and characterof the skins and hides dehaired and bated.

It has been further found that bacterial enzyme preparations, as well as other similar enzyme preparations, such as may be derived from fungi and/or molds, may be prepared in such compositions and utilized under such conditions that it is readily possible to obtain a successive dehairing and hating reaction with resultant pro- 55 duction of hides and skins of very high quality,

which reaction may be most exactly and definitelycontrolled.

Among the preferred enzymatic materials which may be utilized in this connection are bacterial enzymes, such as produced by the growth and propagation of various types of bacilli, particularly Bacillus subtilis and Bacillus mesentericus.

With these bacterial enzyme solutions may be combined or may be included other enzyme materials, such as those derived by the propagation and growth of Aspergillus oryzae, and/or niger. Penicillium glaucum, Mucor delemar, Tryotria: tennis or Amylomyces rowrii, and so forth. Pap i bromelin, trypsin and pancreatin may also be added, if desired.

The dehairing and bating liquors containing these bacterial enzymes should be in sterile condition and substantially devoid of any living micro-organisms and particularly devoid of living bacteria, fungi and ferments, and they most desirably may contain small amounts of organic compounds of disinfectant nature, such as pine oil, phenols, cresylic acids, and naphthols.

In using the bacterial enzymatic or combined enzymatic liquors successively to dehair and bate the skins and hides, it is found preferable to first treat the skins and hides with alkali, preferably with N/8th to N/lOth sodium hydroxide solution.

In the treatment 100 parts of dried weight of goat skins or 200 pounds fresh or salted weight of sheep skins or calf skins may be placed in a bath containing about 800 parts by weight of water and about 4 to 6 parts by Weight of sodium' hydroxide- The alkali is permitted to swell the skins or hides ata gradually decreasing temperature, for example, ranging from 90 F. down to F., and preferably from 86 F. down to F., and the skins or hides are preferably left in the alkali for more than two days and in some cases four, five and so many as tendays having been found satisfactory. I

' After the alkali treatment, and preferably without the intervention of more than twenty four hours, the skin or hide should be Washed with water until preferably it has an alkalinity ranging from pH 10 to 11. The washing in any case should preferably not be carried out to reted and/or the skins or hides may be partly neutralized with solutions of borax and/or with solutions of sodium bicarbonate.

In preparing the dehairing bath about 5 to 10 parts of the bacterial enzyme solution are utilized for every 100 parts of the skin and the skins or hides are placed in the enzyme solution be tween 12 to 36 hours with a preferred time of about 24 hours. The temperature is usually permitted to fall during the dehairing treatment with the solution, temperature of 36 C. being permitted to gradually decrease to 25 C. sothat the enzyme solution is at a substantially lower temperature at the termination of the treatment with the dehairing bath, than at the beginning of such treatment.

It is found satisfactory to add to these dehairing baths ammonium salts, such as ammonium borate and ammonium sulfate, or the salts of reducing sulphur acids, such'as sodium hydrogen sulfite or both together and also in certain instances, urea.

Small amounts of suitable organic disinfectants may also be added to exclude any bacterial growth. After removal of the skins or hides from the dehairing bath they are subject to mechanical dehairing operations and various washing operations, if desired, and then preferably during the same day or within twenty-four hours the skins or hides are placed in a bating bath which is most desirably weaker in enzyme than the dehairing bath and which preferably contains between to of the enzyme strength as the dehairing bath.

Preferably the pH of the bating bath is substantially less than the pH of the dehairing bath by at least one unit and preferably by two or three and a preferred pH range is between 7 to 8 or more, desirably 7.3 to 7.6.

Sometimes ammonium salts, such as ammonium chloride or sulfate may also be added to reduce the pH. Urea and/or sodium bisulfite may also be added.

In order to exclude unwanted bacterial action, small amounts of suitable organic disinfectants may also be added. The skins or hides are permitted to remain in the bating bath for between seventeen to twenty-four hours, and the bath may be permitted to cool during this treatment with the result that its temperature at the conclusion of the treatment can be less than its temperature at the beginning of the treatment.

The hating bath is preferably prepared by strengthening up a previously used bating ba with a minor proportion of a freshly prepared bating bath containing the constituents above referred to. The enzymatic constituents are not destroyed by one bating operation and may be continuously reused, provided the growth of any micro-organism is prevented by the addition of suitable organic substances of disinfecting nature.

As stated above, the preferred enzyme preparatlons include enzymatic liquors produced by the action under aerobic conditions of bacteria or bacilli of the mesentericus or subtilis group upon carbohydrate and protein containing mediums which liquors are utilized as the enzyme preparations in the dehairing process after suitable quantities of the enzyme have formed therein and after substantially all living bacteria and other living organisms have been killed and/or carbohydrates, ammonium salts and mineral constituents, such as salts of potassium, magnesium and calcium and phosphates.

Mediums of this character may be prepared, as for example, by treating or hydrolyzing bran, wheat, or soya bean materials with sulphuric acid and then filtering, and to these nutrient mediums would be added any of the desired mineral constituents which are not present.

The nutrient medium is then preferably neutralized to a pH of between 7.5 to 9.5 and preferably about 8.5 and it is then sterilized, as for example, with steam under pressure and at 140 C. for 35 minutes. Y

After the liquor has been sterilized and its pH has been reduced to about 6.2, it is inoculated with a pure culture of the bacillus of the mesentericus or subtilis families. The culture is allowed to develop at or about room temperature or slightly thereabove, and in one instance a temperature of 30 to 40 C. was found most satis- The antiseptic must be most carefully selected so as not to disadvantageously affect the relatively delicate enzymatic products formed and at the same time must be controlled so that it will assure that there will be no living bacteria present nor any living micro-organisms.

Among the preferred antiseptics which may be employed, preferably in combination are phenol, cresylic acid, beta-naphthol, and other phenol derivatives and preferably consisting of the hydroxylated compounds of mono or poly-alkylated benzenes or of naphthalunes, which may also be halogenated.

The enzymatic liquor which is preferably filtered from insoluble materials contains the proteolytic enzymes and usually desirably also amylolytic and lypolytic enzymes, and in addition metabolic decomposition products of the proteins and carbohydrates, particularly various hexoses, polysaccharides, dextrines, amino acids, peptones, albuminoids, inorganic and organic phosphates, and so forth.

This liquor may be treated to produce the essential enzymatic and metabolic materials in concentrated form by -precipitating with alcohols or various other organic solvents and/or with salt solutions, such as ammonium sulphate solutions, in order to obtain the desired ingredients in solid form.

In the preferred process of the present invention it is desirable that both the dehairing and hating be sterile and contain antiseptic agents to prevent putrefaction and the growth of undesirable micro-organisms. The dehairing action is desirably carried out until the hair is loose and may be readily removed and the subsequent treatment in a bating bath is generally at a decreased pH and enzymatic strength.

Many other changes could be effected in the particular features of process treatment disclosed, and in specific details thereof, without substantially departing from the invention intended to be defined in the claims, the specific description herein merely serving to illustrate certain elements by which, in one embodiment, the

liquors. containing antiseptic agents to prevent putrefaction, which comprises subjecting the skins and hides to successive treatments in bacterial enzyme baths of decreasing pH value and of decreasing enzymaticstrength, the first treatment being sufiicient to loosen the hairs and enable ready removal thereof.

3. A process of dehairing skins and hides,

which comprises first treating the skins and hides with an alkali solution and then successively treating them in bacterial'enzymatic baths containing antiseptic agents to prevent .putrefaction, said baths being of decreasing enzymatic strength and of decreasing pH values, the first treatment being sufiicient to substantially loosen the hairs'and enable ready removal thereof.

4. A process of successively dehairing and bating skins and hides with proteolytic enzymatic I liquors containing antiseptic agents to prevent putrefaction, which comprises subjecting the skins and hides to successive treatments in proteoiyticenzymatic baths of decreasing enzymatic strength the first treatment being sufllcient to loosen the hairs and enable ready removal thereof.

5., A process of successively dehairing and batingskins and hides with proteolytic enzymatic liquors containing antiseptic agents to preventputrefaction, which comprises subjecting. the

skins and hides to a swelling treatment with an alkali and then 'to successive treatments in proteolytic enzymatic baths of decreasing enzymatic strength, the first treatment being sumcient to vloosen thefhairs and enable ready removal thereof.

. 6.. Afiproc'ess oi successively dehairing and bating skins and hides with proteolytic enzymatic liquorslcontaining" antiseptic agents to prevent putrefaction, which comprises subjecting the skins and hides to successive treatments in proteolytic-enzymatic baths of decreasing enzymaticstrength the first. .treatment being suflicient to loosen the hairs and 'oI saidsuc enable ready removal there- A tments each being initiated I cresyiic acids and naphthols.

at a higher temperature than room temperature, and the temperature of the bath being permitted to fall to room temperature during continuation of the treatment. I

7. A process ofsuccessively dehairing and batingskins and hides with proteolytic enzymatic liquors containing antiseptic agents to prevent putrefaction, which comprises subjecting the skins and hides to successive treatments in proteolytic enzymatic baths of decreasing enzymatic strength, the first treatment being suiilcient to loosen the hairs and enable ready removal thereof, the hides and skins being permitted to remain in said enzymatic baths ior, between 12 to 36 hours.

8. A process of successively dehairing and betting skins and hides with bacterial enzymatic liquors containing antiseptic agents to prevent putrefaction, which comprises subjecting the skins and hides to successive treatments in at least two bacterial enzymatic baths of decreasing enzymatic strength, the first treatment being suflicient to loosen the hairs and enable ready removal thereof, said first bath used being maintained at a pH of between 10 and 11 and said second bath used being maintained at a pH oi between 7 and 8. a

9. A process of successively dehairing and bating skins and hides with proteolytic enzymatic liquors containing antiseptic agents to prevent putrefaction, which comprises subjecting the skins andhides to successive treatments in at least two proteolytic enzymatic baths of decreasing enzymatic strength, the first treatment being sufllcient to loosen the hairs and enable ready removal thereof, said second bath used containing an ammonium salt.

10. A process of successively dehairing and bating skins and hides with proteolytic enzymatic liquors containing antiseptic agents to prevent putrefaction. which comprises subjecting the skins and hides to successive treatments in at least two proteolytic enzymatic bathsof decreasing enzymatic strength, the first treatment being sumcient to loosen the hairs and enable ready removal thereof. said first bath used containing an ammonium salt.

11. A process of successively dehairing and hating skins and hides with proteolytic enzymatic liquors containing antiseptic agents to prevent putrefaction, which comprises subjecting the skins and hides to successive treatments in proteolytic enzymatic baths of decreasing enzymatic strength, the first treatment being suflicient to loosen thehairs and enable ready removal thereof, said baths eachcontaining one of a group of disinfectants consisting of pine oil, phenols LEO WALLERSTEIN. JULIUS PFANNMULLER.